A liquid crystal panel used in, for example, a liquid crystal display device such as a liquid crystal television set does not emit light, and therefore requires a backlight unit separately. The backlight unit required is to be installed on the back side (side opposite to the display surface) of a liquid crystal panel, and includes: a chassis having an open surface on the liquid crystal panel side; a light source housed inside the chassis; and optical members (such as a diffuser sheet) arranged in the opening of the chassis and used for effectively irradiating, toward the liquid crystal panel, light emitted by the light source. Additionally, the backlight unit is made thin by using a light guide plate, which has a light entering surface and a light exiting surface, and by providing the light source on the light entering surface provided on an end section of the light guide plate. One known example disclosing this kind of backlight unit is one described in Patent Document 1 below.
In the backlight unit described in Patent Document 1, the light guide plate includes two light guide plates: a first light guide plate and a second light guide plate. The light guide plate has a configuration where the first light guide plate and the second light guide plate are placed over each other with the light exiting surfaces of the first and second light guide plates being set along the same direction and with the light entering surfaces of the first and second light guide plates being set facing each other, and the light sources are placed in positions relatively close to the respective light entering surfaces. Note that Patent Document 1 assumes that a direction taken by light exiting from a general light guide plate forms an angle of about 60 to 70 degrees with a direction along the normal line of the light exiting surface of the light guide plate. This structure has the light exiting surfaces of the first and second light guide plates placed so as to face each other, and thereby makes it possible to obtain a backlight unit from which light exits in two directions.    Patent Document 1: Japanese Unexamined Patent Publication No. 2008-77946